Capacity limitation in short-term visual memory for contour curvature

摘要

The difference threshold for contour curvature in short-term visual memory (STVM) was measured in two-interval forced-choice by partial discrimination. In experiment I the study stimulus consisting of 1 to 4 curved contours was briefly presented, after retention interval, followed by a single contour as the test stimulus. The subject's task was to judge the test had higher or lower curvature than the corresponding study contour. The present procedures were designed in such a way as the set-size effects in the study stimulus could depend on the limitations both in encoding and STVM in experiment 1 and only in STVM in experiment. The results both in experiment 1 and 2 showed that the Weber fraction was elevated with the number of study contours. They clearly indicated that only one object could be retained in STVM with more fidelity, and that STVM indeed has limited capacity. Otherwise, the Weber fraction was not extremely higher for 4 contours compared with for 1 one, which was interpreted that at least 4 objects could be retained in STVM with some fidelity.